The present invention relates to a floating plane for press punches, which substantially comprises an isostatic support or base on which the fixing of a punch is performed by means of an intermediate partition, filled with non-compressible fluid such as oil, including a stiff wall corresponding to the plane of said isostatic base and an opposite wall of elastic material, such as rubber or the like, whereon the punch is coupled.
The stable coupling between said isostatic base and said punch is obtained by vulcanized means or by sliding water-tight through pins or the like.
During the pressing steps, particularly for ceramic tile pressing, the non-compressible oil or fluid contained in the intermediate partition presses on its elastic wall and, consequently, on the punch coupled thereto, with a substantially uniform pressure on the whole surface, regardless of the weight concentration and/or concentration of the clays to be pressed. This allows the punch to be appropriately oriented, compensating any loading unevenness of the clays and/or powders in the moulds, oscillating on its whole surface.
In fact, it is known that clay pressing for the formation of ceramic products, such as for example tiles, causes serious problems.
In particular, the powder loading is quite often uneven with respect to the volume and the density inside the moulds, with consequent uneven pressing on the tile surfaces and irregular shrinkage in the subsequent firing, which involve considerable waste percentages or product declassing.
Recent technological innovations have determined the use of isostatic pressings which comprise punches with fluid circulation; even though these innovations allow to achieve uniform pressing with elimination of size variations, convexities and deformations of the pressed or fired products, they have other drawbacks caused by limitations in the shapes of the tile lower parts, with consequent problems on the outer sides of glazed and fired tiles. Furthermore this kind of equipment is very expensive.
Other more recent and innovative solutions have solved said problem by means of floating planes fixing the punches to the presses which are coupled to plates made of elastic material, in which some floating elements are fixed and are matched with hydraulic pistons sliding in seats provided on intermediate plates.
These intermediate plates are fixed to bases including hydraulic ducts for feeding said pistons.
During the pressing, the non-compressible fluid present in the ducts works on the pistons proportionally to the distribution of thickness and/or density of the powders to be pressed, which are discharged on the moulds.
Although these solutions have achieved excellent results and guarantee very high quality products, they are still quite expensive as far as manufacturing costs.
Another embodiment consists in that on the even surface of a support or base there is a hydraulic duct on metal sheet with a thickness of few tenths (5.div.6/10) mm. An elastic layer, for example rubber, with a thickness of few tenths (5.div.6/10) mm is applied thereon, for example by vulcanization.
Even this embodiment does not achieve the intended aim as regards the position and the evenness of density of the pressed material.
The aim of the present invention is to eliminate the above-mentioned drawback.